Some of it definitely is. Part of it is nostalgia for me. I went there so much as a kid when I go back I have a crapload of happy childhood memories. However there are certain things I'll never be too old for at Disneyland. Big Thunder Mountain, Space Mountain, Splash Mountain, Matterhorn, etc. Cal Adventure has several universally enjoyable rides as well. Universal might be better though for all adults. Honestly Magic Mountain would be the best place of all if they're thrill seekers.